1. Field of the Invention
The field of the invention relates to a cooler for a belt type stageless transmission, which is used in a power unit of vehicles such as motorcycles.
2. Description of the Prior Art
The cooler for a belt type stageless transmission is disclosed in Japanese Patent Publication Laid-Open No. 109762/1983, for example.
In such conventionally known coolers, a centrifugal fan is provided integrally on the back surface of a variable diameter pulley of a belt type stageless transmission, so that the open air is introduced into a transmission casing by the centrifugal fan to cool the transmission. However, heated portions such as a contact portion of the variable diameter pulley with a transmitting V-belt are not sufficiently cooled by only the centrifugal fan and thus, an intended cooling effect cannot be achieved.
In addition, to cool the interior of the transmission chamber of the transmission, it is a conventional practice to introduce the open or outside air into the transmission chamber through an air intake port opened in the front portion of the transmission casing and to discharge it through an air exhaust port opened in the rear portion of the transmission casing. In this case, the air flowing along the lower surface of the transmission casing and entraining water, mud, dust or the like therein may enter the transmission chamber through the air exhaust port, or the air may be drawn in the vicinity of the exhaust port to obstruct the smooth exhaust flow of the cooling air in the transmission chamber.
Further, where the transmission chamber containing the stageless transmission therein is disposed on one side of an engine body adjacent thereto, the combustion heat from the engine body may be transferred to the transmission casing to raise the temperature within transmission casing. Thus, the stageles transmission may be thermally damaged, and its service life disadvantageously shortened.